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828 Dosage > Lecture 4: Dry Powder Inhaler > Flashcards

Lecture 4: Dry Powder Inhaler Flashcards

1
Q

Inhalation dosage forms

A

-local and systemic

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2
Q

Local application of inhalation dosage forms

A

-high local concentration
-fast action
-lower systemic side effects
-asthma, COPD, lung infection

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3
Q

systemic application of inhalation dosage form

A

-rapid absorption
-fewer drug-metabolizing enzymes

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4
Q

fluticasone

A

-less than 1% bioavailability in oral form bc of first-pass effect
-plasma binding is more than 99% (less than 1% of drug available)
-systemic adminstation = side effects (hypercorticism)

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5
Q

Inhaled fluticasone

A

-absolute bioavailability (~10%)
-safe for children under 1

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6
Q

Aystemic application of inhaled medicines

A

-300-500 million alveoli in lungs
-huge surface area of lungs

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7
Q

Alveoli

A

-surrounded by lung capillaries
-thin walls for gas exchange (good for absorption)
-nonciliated

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8
Q

Respiratory tract regions

A

-extrathoracic (head and neck)
-upper bronchial region (trachea and bronchi)
-lower bronchial region (braonchioles)
-alveolar region

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9
Q

Bronchi

A

-large ciliated airways

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10
Q

bronchioles

A

-small ciliated airways

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11
Q

Particle deposition mechanisms

A

-diffusional transport
-inertial transport
-gravitational transport

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12
Q

diffusional transport

A

-ultrafine particles
-alveoli
-tend to be exhaled without depositing
-alveolar region

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13
Q

Gravitational transport

A

-sedimentation
-slightly bigger particles than diffusional
-increase with diameter and density
-bronchial and alveolar region

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14
Q

Inertial transport

A

-impaction
-driven by momentum
-increase with particle velocity, diameter, density
-extrathoracic region

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15
Q

Sedimentation increases with:

A

-density
-acceleration due to gravity
-diameter
-slip correction factors

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16
Q

Sedimentation decreases with:

A

-shape factors
-viscosity

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17
Q

sedimentation equation

A

-terminal settling velocity

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18
Q

Aerodynamic diameter (Dae)

A

-diameter of particle with unit mass density of 1g/cm3 that would settle at the same velocity as particle of interest
-EQUATION SLIDE 10

=(density)^0.5 x Dgeo

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19
Q

Particles with aerodynamic diameter > 5 um

A

-deposit in upper airways
-due to inertial impaction

20
Q

particles with aerodynamic diameter 1-5 um

A

-deposit in lower airways

21
Q

particles with aerodynamic diameter <1 um

A

-exhaled

22
Q

Defense mechanisms of the upper airways (head airways)

A

-filtering mechanisms in nasal cavity
-trap and eliminate large particles
=sneezing and coughing

23
Q

Defense mechanisms of conducting airways (lung airways)

A

-mucocilliary escalator
-IgA

24
Q

Defense mechanisms of alveoli

A

-alveolar macrophages
-immunologic mechanisms: T and B lymphocytes; IgG

25
Q

Types of aerosols: liquid droplets

A

-pressurized meter-dose inhalers (pMDIs)
-nebulizers

26
Q

types of aerosols: dry particles

A

-dry powder inhalers (DPIs)

27
Q

Propellant-driven (pressurized) metered-dose inhalers (pMDI)

A

-small volume of pressurized drug dispersion is isolated in a metering chamber
-released through spray orifice
-drug propelled from container, forming spray droplets after equilibriating with atmospheric pressure

28
Q

pMDI pros/cons

A

-need good inhalation technique
-lung deposition efficiency is typically low: 5-20%
-high droplet velocity leads to extensive deposition of drug in oral areas (80%)
-drug/solvent compatibility issues with propellant
-only suitable for low-dose medications
-less expensive

29
Q

components of pMDI

A

-drug
-propellant (CFC or HFA)
-cosolvent (ethanol)
-surfactant (sorbitan trioleate, oleic acid, lecithin)

30
Q

Nebulizers

A

-generate droplets of drug dispersion using ENERGY from compressed air or piezoelectric ceramics
-delivered via INSPIRATORY flow
-suitable for treatment of young and elederly patients and emergency treatment

31
Q

Jet nebulizers

A

-more time consuming than pMDIs
-require hygienic maintenance of equipment
-bulky
-low efficiency (10-15% of drug deposited)

32
Q

New nebulizers

A

-smaller than traditional jet nebulizers
-higher delivery efficiency
-lower residues

-vibration mesh nebulizer and soft mist inhaler

33
Q

Dry powder inhalers (DPI)

A

-dry particles in inhaler device
-aerosol of dry powder created by airflow carries particles to lungs
-deposited dose 5-40% based on formulation, device, and airflow

34
Q

DPI uses

A

-asthma, COPD, lung infections
-insulin

35
Q

Breath-actuated passive devices (passive DPI)

A

-powder aerosols generated by patients’ inspiratory airflow
-performance of a device could be highly variable among patients
-passive

36
Q

Power-assisted active devices (active DPI)

A

-mechanical or electrical energy generates powder aerosols
-less dependent on patient’s inspiration capability
-active

37
Q

single unit-dose DPI

A

-smaller inhaler
-simple design

38
Q

multiple unit-dose

A

-convenient for frequent use
-inhaler larger
-design is complex

39
Q

Particle production

A

-mechanical milling
-spray drying

40
Q

jet milling (mechanical milling)

A

-apply mechanical forces to break up particles
-particles are typically cohesive with high surface energy and high electrostatic charge
-POOR flowability and POOR aerosolization performance

41
Q

Spray drying

A

-drug dissolved into solvent
-atomized into small droplets
-dried by hot airflow through solvent evaporation

42
Q

Particle interaction

A

-van der waals
-electrostatic (significant in dry conditions)
-capillary forces (signififcant for hygroscopic particles at high humidity
-mechanical interlocking

43
Q

carrier-based DPI formulations

A

-act as filler for low-dose drugs
-improve flowability

43
Q

Particle deposition is influenced by

A

-particle geometric diameter
-density
-morphology
-surface energy
-electrostatic charge
-hygroscopicity

43
Q

Aerosol performance depends on carrier properties:

A

-particle geometric diameter
-morphology
-surface energy
-electrostatic charge
-drug to carrier ratio
-addition of additives

828 Dosage (27 decks)

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